Area Forecast Discussion
Issued by NWS Raleigh/Durham, NC
Issued by NWS Raleigh/Durham, NC
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237 FXUS62 KRAH 060014 AFDRAH Area Forecast Discussion National Weather Service Raleigh NC 814 PM EDT Wed Jun 5 2024 .SYNOPSIS... A series of mid-level disturbances will move east and interact with an unseasonably moist airmass over NC through Thursday. A pre- frontal trough and cold front will move across the area Thursday evening through early Friday. High pressure will move in with fair weather for the weekend. && .NEAR TERM /THROUGH TONIGHT/... As of 300 PM Wednesday... As surface high pressure off the Mid-Atlantic coast continues to pump warm moist air into the region from the south, with showers and storms continuing to develop over the next few hours. Best chance for storms this afternoon will be along and east of US1. This is also the area where WPC has a marginal risk for flash flooding. While coverage will once again be isolated this afternoon and evening PoPs remain at around 30-45% chance for areas until at least midnight. After midnight atmosphere should destabilize and a few showers could still be possible with the upper distance moving overhead. Clouds are expected to stick around through the morning before clearing out after sunrise. Lows are expected to be above average with temps ranging from upper 60s to low 70s. && .SHORT TERM /THURSDAY AND THURSDAY NIGHT/... As of 230 PM Wednesday... ...There is a Level-1/Marginal Risk For Severe Storms mainly along and north of HWY 64... Central NC will lie along the southern fringes of a mature mid- latitude cyclone that will traverse along southern Ontario and the Upper Great Lakes. Meanwhile, the associated belt of enhanced westerlies will dip down into the Ohio Valley and northern mid- Atlantic states with the trailing surface front crossing the area Thursday night. The day should start start out mostly dry with a near repeat performance of gradual lifting of the overnight/morning stratus layer through the late morning/midday. Thereafter, a loosely organized line of showers and storms, likely focused along the H8 trough/front, will move east off the mtns and foothills and into the western Piedmont between 18-21z. The convection is expected to move east through the remainder of the afternoon and evening hours, before exiting the eastern/coastal plain counties ~03z. It is unclear how the line will evolve as it moves eastward. However, there is a increasing signal in the latest hi-res model guidance that the line could weaken significantly after sunset, especially across the southern and southeastern portions of the forecast area. Deep layer shear over NC has also trended weaker in recent runs, with some of the guidance indicating a slight increase to 25-30 kts, in a narrow belt extending along the NC-VA late towards sunset. If there is chance for any isolated strong to severe storm, it will likely be across the northern tier counties between 4-8 pm. Damaging wind gusts are the primary threat. Highs will be warmer than today, especially across the eastern half of the forecast area where the later arrival of showers and storms should allow for some strong heating. Highs ranging from mid 80s NW to lower 90s SE. Some isolated showers will be possible overnight/predawn hours Friday morning as the lagging cold front crosses the area. Lows 65- 70. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... As of 200 PM Wednesday... Friday and Saturday: Aloft, an upper low will meander slowly eastward through southern Ontario/southern Quebec, Canada Fri and Sat. The attendant trough will progress eastward through the East Coast states Fri as a s/w passes over central NC within the trough. The trough will continue offshore Fri night. Nearly zonal flow should prevail Sat/Sat night, with a weak s/w or two passing overhead. At the surface, the cold front should be through central NC Fri morning and continue eastward offshore through the aft/eve. Cool high pressure centered just west of the southern Appalachians will ridge eastward into the area Fri night. A trough may develop over the area Sat and amplify Sat night, while the high weakens. For now the forecast remains dry. Highs Fri ranging from low/mid 80s NW to mid/upper 80s SE, with lows ranging from mid 50s north to mid 60s south. Temps should be similar Sat/Sat night, highs a degree or two lower and lows a couple/few degrees higher in some spots. Sunday onward: There is still some uncertainty in this part of the forecast, so confidence is on the low side. Aloft, as the parent low swings through Quebec, Canada and the Northeast US a potent s/w will drop south out of central Canada, through the northern Plains/upper MS Valley Sat night/Sun, then continue around the parent low through the Great Lakes/OH Valley Sun, amplifying the attendant trough in the process. As the low lifts northward Sun night/Mon, the trough should swing eastward into (GFS)/toward (ECMWF) the mid-Atlantic. The s/w should move through central NC Mon night or Tue/Tue night. At the surface, with the trough over central NC, a warm front may briefly lift through the area Sun aft/eve, before another cold front pushes through the area Sun eve/night. The front should stay east of the area, with high pressure over the Plains/MS Valley through Mon night. Beyond that, the medium-range guidance varies greatly, with the ECMWF showing a low tracking along the Southeast US/Carolina coast Mon night and Tue, while the GFS slowly develops a westward retreating, inverted coastal trough Tue/Wed. The best chances for showers/storms will largely be tied to the initial s/w sometime between Sun eve and Mon night. Additional showers/storms will be possible through mid-week, but confidence is low at this time. Temperatures should be within a category or two of normal. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... As of 810 PM Wednesday... 24-hour TAF period: The broken band of showers over the northern and western Piedmont will continue to weaken as it pushes east this evening, with no significant aviation impacts expected. Just mid and high clouds will stream across central NC, before IFR/MVFR low stratus again develops late tonight by around 08-10z. The highest confidence of this occurring is at the Triad terminals (INT and GSO), followed by RDU and FAY, and lastly RWI. S/SW winds should stay elevated overnight (around 5-10 kts) and this combined with the low stratus mean fog is not expected to be a concern. Conditions will improve to VFR by mid to late morning, but a line of showers and storms associated with a cold front is expected to move east through central NC during the afternoon and evening. The best guess is for the line to reach the Triad terminals by mid afternoon, followed by RDU near the end of the TAF period, though timing is still a bit uncertain. MVFR or even IFR ceilings and visibilities will be possible as the line moves through, along with gusty winds. Outlook: The line of showers and storms will continue to impact southern and eastern parts of the area through the evening, with sub-VFR conditions still possible. VFR conditions and dry weather are expected to return Friday through the weekend before another cold front and upper disturbance bring more shower and storm chances late Sunday into Monday. && .RAH WATCHES/WARNINGS/ADVISORIES... None. && $$ SYNOPSIS...CA/MWS NEAR TERM...CA SHORT TERM...CBL LONG TERM...KC AVIATION...Danco